Stringing Things Along - Elementary School (
Page 2 of 7 )
Let's start with the basics. In
JavaScript, the term "string" refers to a sequence of characters. The following
are all valid examples of strings:
"hey wassup?"
"I ROCK!"
"a long time ago in a galaxy far, far
away"
String values can be assigned to a variable using
the standard assignment operator.
<script language="Javascript">
var myStr = "Elementary, my dear Watson";
</script>
String values may be enclosed in either double quotes
("") or single quotes('') - the following variable assignments are
equivalent:
<script language="Javascript">
var myStr = "Elementary, my dear Watson";
var myStr = 'Elementary, my dear Watson';
</script>
This comes in handy when you need to embed HTML code
in your JavaScript strings, and don't want the various sets of quotes to
conflict with each other. Consider the following example, which
illustrates:
<script language="Javascript">
// bad
var myStr = "<a href="http://www.melonfire.com">Home</a>";
// good
var myStr = '<a href="http://www.melonfire.com">Home</a>';
</script>
You can also take the scenic route, and define a
string using JavaScript's built-in String object, as below:
<script language="Javascript">
var myStr = "Elementary, my dear Watson";
// this is equivalent
var myStr = new String();
myStr = "Elementary, my dear Watson";
// and so is this
var myStr = new String("Elementary, my dear Watson");
</script>
When you do this, you create a proper JavaScript
object, and thereby have access to all the methods and properties of that
object. Note that it's not essential to create strings using the second
technique outlined above; it's far more common (not to mention easier on your
keyboard) to use the first one, because the JavaScript interpreter automatically
converts string datatypes into string objects whenever necessary.
If
you're a JavaScript newbie, this next example won't do much for you - but for
those of you who are purists, this next code snippet will help in making the
distinction between a datatype and an object clearer.
<script language="Javascript">
var myStr = "Hit me";
// this returns "string"
alert(typeof(myStr));
var myStr = new String("Hit me");
// this returns "object"
alert(typeof(myStr));
</script>
You can concatenate strings with the addition (+)
operator - as the following example demonstrates:
<script language="Javascript">
var fname = "James";
var lname = "Bond";
// concatenate the two, separate with a space
var name = fname + " " + lname;
</script>
If your string contains quotes, carriage returns or
backslashes, it's necessary to escape these special characters with a backslash.
<script language="Javascript">
// will cause an error due to mismatched quotes
var movie = 'Baby's Day Out';
// will be fine
var movie = 'Baby\'s Day Out';
</script>
Try it out yourself and see, and then flip the page
to see how to dress up your strings.
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